The Justice Department contended in a sealed brief yesterday that the Secret Service should be allowed to invoke an untested legal privilege to block testimony by its officers about President Clinton's relationship with Monica S. Lewinsky, officials said.

Clinton does not need to invoke the privilege because it belongs to the Secret Service as essential to the job of protecting the president, the Justice Department said in the brief submitted to U.S. District Judge Norma Holloway Johnson.

Law enforcement sources said a letter from former president George Bush supporting the government's position was attached to the brief.

[The Associated Press reported that Bush's filing supported the Justice Department position. "If a president feels that the Secret Service agents can be called to testify about what they might have seen or heard, then it is likely that the president will be uncomfortable having the agents nearby," MSNBC quoted Bush's letter as saying. "If that confidence evaporates, the agents denied proximity cannot properly protect the president." In Houston, Jean Becker, Bush's chief of staff, confirmed that Bush had written Secret Service Director Lewis C. Merletti last week, but described it as a private letter and would not discuss it contents.]

The pleading came in response to a sealed April 3 motion by independent counsel Kenneth W. Starr to compel several Secret Service uniformed officers and plainclothes agents to answer questions about what they might have seen or heard of the former White House intern's encounters with the president.

Sources familiar with his argument said Starr contends that Clinton himself must invoke the privilege, but the White House said yesterday that neither the president nor his lawyers have become involved in the matter and that they take no position on it.

"The president believes for his sake and for the sake of future presidents that this ought to be dealt with by the Treasury Department, the Secret Service, and argued by the Justice Department," White House press secretary Michael McCurry told reporters. "And we've taken no position whatsoever in the matter."

In another development yesterday, relatives of Linda R. Tripp, Lewinsky's onetime friend who secretly tape-recorded her conversations about Clinton, said they are establishing a Web site and a legal defense fund to pay her lawyers. Tripp is a cooperating witness in the Starr investigation.

"Linda doesn't have the money to meet the cost thrust upon her by the Independent Counsel's investigation," Tripp's brother-in-law, Christopher Caposella, said in a statement. He said her family is angered by the "bruising scrutiny and outrageous assaults on her character."

Tripp, he said, "listened to a woman's talk of infidelities, she didn't create them. It was Monica's behavior and choices, not Linda's actions, that put this story on the front pages. Linda was forced into an impossible and frightening situation."

In the privilege dispute, Secret Service Director Lewis C. Merletti has argued that agents and officers should never disclose "any aspect of the personal lives of our protectees," even after they have left the agency. But Starr's motion was directed only at current members of the Secret Service and the government's claim of privilege was limited to them, according to law enforcement sources.

A former member of the Secret Service's uniformed division, Lewis C. Fox, said this week that he told the grand jury that he saw Lewinsky enter the Oval Office on a weekend day in the fall of 1995 and that Clinton told him and a plainclothes agent who was also on duty to "close the door" because "she'll be in here for a while."

Officials at Treasury, the Secret Service's parent agency, have argued that unless members of the Secret Service can be barred from testifying, presidents will no longer trust them.

But law enforcement officials said they recognize there are limits to the claimed protective privilege. They said, for example, that if agents should see a president engaging in conduct that is itself a crime, such as taking a bribe, they could be required to testify.